A late Mauricio Pinilla penalty gave Atalanta a dramatic 2-1 victory over Inter to increase pressure on beleagured Nerazzurri boss Frank De Boer.
Eder's second-half piledriver looked to have salvaged a point for Inter, before Pinilla stepped up to stroke in an 88th penalty and condemn the visitors to a third consecutive Serie A defeat.
Atalanta defender Andrea Masiello's close-range header in the early stages was just reward for a first half the hosts dominated as De Boer's men struggled for any sort of fluency, before a marked improvement in the second period.
But Pinilla's late spot-kick takes Atalanta above Inter in the Serie A standings and leaves De Boer's men winless in four straight league games, turning up the heat on the Dutchman.
Inter are without a win in Serie A since beating Empoli on September 21 and host Torino on Wednesday with De Boer desperate to kickstart his side's flagging campaign.
Atalanta broke the deadlock after just 10 minutes, the goal scored via a beautifully worked corner routine, with Masiello emerging unmarked at the far post to nod in after a clever flick-on from Jasmin Kurtic.
It could have been two just minutes later, but Samir Handanovic palmed away an Andrea Conti header.
The Slovenian goalkeeper was again alert to parry a swerving Rafael Toloi strike 10 minutes before the interval.
Inter looked every part a side which has struggled for rhythm this season, frequently giving the ball away and struggling to create chances during the first half. A square ball into vacant space by Ivan Perisic after a bursting forward run to the byline summed up their lacklustre attacking play.
Appeals for an Inter penalty were waved away when Eder went down under the challenge of Remo Freuler.
De Boer must have made his thoughts known at the interval, as Inter emerged in the second period with a far greater intensity to their play.
It was rewarded on 50 minutes, when Eder squared proceedings with an outstanding drive into the top corner after the Italy international striker was teed up from a free-kick 25 yards from goal.
Atalanta manager Gian Piero Gasperini was sent to the stands against the side he managed for a brief period in 2011, seemingly for his protestations about the award of the free-kick that led to Eder's equaliser.
Home keeper Etrit Berisha then denied Perisic as Inter pressed for a rapid turnaround, palming away his strike.
Play became stretched during the second half as both sides looked for a decisive second goal.
Handanovic was again forced to react smartly to repel headers from Abdoulay Konko and Pinilla as Atalanta threatened to retake the lead.
Perisic again almost grabbed all three points for Inter but his fiercely struck left-footed drive was again saved by Berisha.
But there was time for late drama when Davide Santon felled Franck Kessie with a wild challenge in the area, allowing Pinilla to step up and nervelessly slam beyond Handanovic into the top corner to gain all three points for Atalanta.